Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
  • A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
  • A61M5/16877—Adjusting flow; Devices for setting a flow rate
  • A61M5/16881—Regulating valves
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D7/00—Control of flow
  • G05D7/01—Control of flow without auxiliary power
  • G05D7/0106—Control of flow without auxiliary power the sensing element being a flexible member, e.g. bellows, diaphragm, capsule
  • G05D7/0113—Control of flow without auxiliary power the sensing element being a flexible member, e.g. bellows, diaphragm, capsule the sensing element acting as a valve
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T137/00—Fluid handling
  • Y10T137/7722—Line condition change responsive valves
  • Y10T137/7781—With separate connected fluid reactor surface
  • Y10T137/7784—Responsive to change in rate of fluid flow
  • Y10T137/7787—Expansible chamber subject to differential pressures
  • Y10T137/7788—Pressures across fixed choke

Definitions

• the present invention relates to the control of low fluid flows. More particularly, the invention provides a variable flow regulator able to provide accurate flow rates, at low flow and ultra low flow rates, typically as required in medical and laboratory applications.
• Medicines not taken by mouth can be added to an infusion, or are injected by the use of a syringe having a hollow needle, the contents of a 5 to 25 ml ampoule being received by the patient in 2 - 5 seconds. These methods cannot be utilized where medical fluids are to be received by the patient at controlled and very slow feed rates, typically under 10 ml per hour.
• Such time-extended flow requires a source of power other than the finger pressure of a medical attendant on a syringe plunger.
• the power source can be gravity or an elastic element, in combination with a flow regulator, or an electrically driven pump can be used with or without a flow regulator.
• Portable devices normally powered by electric batteries, can serve this purpose.
• Adjustable flow, mains electricity-driven metering pumps are used in industrial and chemical applications, and for dispensing, for example, liquid fertilizers, chlorine and fluoride.
• a positive displacement peristaltic pump of this type marketed under the MECOMATIC trade name can be adjusted down to 0.25 gallons per day. Although the tubing can be readily changed, this pump weighs 9.5 lb. and is obviously not disposable, and such pumps are not suitable for medical applications requiring extremely slow flow rates.
• US Patent No. 4,544,369 Skakoon et al disclose a battery-operated miniature syringe infusion pump.
• the device includes a battery, a DC motor, gearing, electronic controls, a lead screw, a force-sensing system, indicators, and alarms and is light enough to be mounted on an IV pole.
• the main drawbacks are high initial costs, lack of portability and the need for batteries.
• US Patent no. 5,034,004 to Crankshaw is generally similar to the Skakoon specification but involves even more mechanical and electronic components.
• Yet a further object of the present invention is to provide a self-powered regulator for delivering fluids at very low flow rates.
• the present invention achieves the above objects by providing a wide-range flow regulator for low fluid flows, comprising a housing divided into a first and a second chamber by means of an elastic diaphragm, said first chamber having an inlet for a fluid, and an outlet connected to a labyrinth path.
• the second chamber has an inlet connected to an outlet of said labyrinth path, the outlet of said second chamber being an inlet at an extremity of a discharge tube, the discharge tube inlet being positionable at a short distance from the diaphragm.
• Means are provided to vary said distance to achieve fine adjustment of the flow rate, the discharge tube inlet being sealed by the diaphragm when said diaphragm flexes in response to pressure drop in the second chamber.
• the labyrinth path connects the first chamber to the second chamber to allow the liquid to flow under controlled pressure drop from the first chamber to the second chamber and so to intermittently raise pressure in the second chamber to temporarily separate the diaphragm from the discharge tube inlet. This allows liquid to enter and traverse the discharge tube for use of said fluid.
• Means are provided to selectively short-circuit at least a portion of the labyrinth path to vary the range of the fluid flow rate.
• a flow regulator wherein the inlet of said first chamber is connectable to receive fluid by gravitational means.
• a flow regulator wherein said inlet of the first chamber is connectable to receive fluid from a syringe.
• the performance of the Bron device is dependent on the stiffness of the flexible diaphragm. Such stiffness can vary widely with conditions of age, humidity and exposure to chemical attack.
• the present invention in addition to labyrinth length adjustment, also provides means for fine adjustment of flow rates, by providing means for adjusting the distance between the diaphragm and the inlet of the discharge tube. Consequently the device of the present invention can be used over a very wide range, typically from 1 to 200 ml per hour.
• the stiffness of the diaphragm has little effect on performance, as a spring provides the force needed to press the diaphragm into contact with the regulator inlet.
• novel regulator of the present invention can be mass produced by plastic injection molding of its individual parts and that assembly of the components can be effected in very little time - easily in less than a minute. Consequently the device can be marketed for disposable use, as is preferred for medical applications.
• FIG. 1 is a sectional elevation of a preferred embodiment of the low flow regulator according to the invention.
• FIG. 2 is a sectional elevation of a diaphragm used in the regulator
• FIGS. 3a & 3b are plan and sectional views of a spring used in the regulator
• FIG. 4 is a perspective view of the conical member carrying the labyrinth path
• FIG. 5 is a sectional elevation of a second embodiment of the regulator; and FIG. 6 is an elevational view of a powered syringe connected to a very low flow regulator.
• FIG. 1 There is seen in FIG. 1 a wide-range flow regulator 10 for low fluid flows.
• the regulator 10 is contained in a housing 12, which is divided into a first 14 and a second chamber 16 by means of an elastic diaphragm 18.
• the housing 12 is suitably made of a hard plastic, for example ABS.
• the first chamber 14 has an upper inlet 20 for a fluid, this inlet being connected to a tapered mouth 22.
• the inlet 20 is connected to receive fluid by gravitational means, using a tube 24 connected to a fluid supply such as a suspended medical infusion bag 26.
• fluid flow is adjustable between about 10 to about 200 ml per hour.
• the outlet from the first chamber 14 in the present embodiment comprises a gap 30 between the diaphragm 18 outer diameter and the housing 12, allowing fluid to enter an upper inlet 32 of a labyrinth path 34 formed in the outer face of a hollow conical member 36, seen more clearly in FIG. 4.
• the second chamber 16 has an inlet aperture 38 alignable to a full path length outlet 40 of the labyrinth path 34.
• the outlet of the second chamber 16 comprises an inlet 42 at an extremity of a discharge tube 44.
• the discharge tube inlet 42 is positionable at a short distance from the diaphragm 18. Means such as the screw thread 46 shown are provided to vary this distance, thereby to achieve fine adjustment of the flow rate. Reducing this distance reduces flow rate, an increase increases flow.
• the discharge tube inlet 42 is sealed by the diaphragm 18 when the diaphragm flexes downwards in response to pressure drop in the second chamber 16.
• the labyrinth path 34 connects the first chamber 14 to the second chamber 16 to allow the liquid to flow under controlled pressure drop from the first chamber 14 to the second chamber 16. Such flow intermittently raises pressure in the second chamber 16, and temporarily separates the diaphragm 18 from the discharge tube inlet 42. This allows fluid to enter and traverse the discharge tube 44 for use of the fluid. To prime the regulator 10 for use, air is removed by allowing free flow through the discharge tube 44.
• Means, such as intermediate apertures 48, and 56 seen in FIG. 4, through the labyrinth path 34 are provided to selectively short-circuit at least a portion of the labyrinth path 34 to vary the range of the fluid flow rate.
• a revolvable seal flange 50 is accessible to the user by means of its projecting outer diameter 52. The user may thus turn the seal flange 50 relative to the hollow conical member 36 and housing 12; the latter two components retain a fixed relationship to each other.
• the seal flange 50 carries the inlet aperture 38 which is alignable with alternate outlet apertures 40, 48, 56, of the labyrinth path 34.
• the seal flange 50 is made of a medium hardness plastic, for example a polyester.
• a spring 62 urges the diaphragm 18 away from the discharge tube inlet 42.
• the regulator 10 is advantageously configured for disposable use. Its components are designed for plastic injection molding to allow low cost high volume economic manufacture.
• the fluid path in the present embodiment is as follows:
• a diaphragm 18 having a thick outer ring 64 serving as a seal element.
• a central disk 66 has a first 68 and a second opposite face 70. When assembled in the regulator 10, first face 68 is in proximity to the first chamber upper inlet 20.
• the second face 70 is configured to seal the discharge tube inlet 42.
• a thin flexible section 72 connects outer ring 64 and central disk 66.
• the flexible section can withstand bending without high strain due to being only about 0.5 - 1 mm thick. The low strain improves reliability of this component.
• the diaphragm 18 is suitably made of a silicon elastomer.
• FIGS. 3a & 3b illustrate a spring 62, which when in use urges diaphragm 18 away from discharge tube inlet 42.
• the spring 62 comprises an outer ring 74 retained in second chamber 16, a central disk 76 configured to press against the central disk 66 of the diaphragm 18, and a plurality of curved arms 78 connecting outer ring 74 and central disk 76.
• spring 62 makes possible the exertion of a high force in the small space available for its operation. Suitable materials therefore are stainless steel and ABS.
• FIG. 4 Seen in FIG. 4 is the hollow conical member 36 previously seen in FIG. 1.
• the labyrinth path 34 comprises an open channel disposed on the outer face 80.
• the member 36 When in use, the member 36 is positionally fixed inside housing 12 so allowing the conical inner face of housing 12 to provide a leak-proof seal for the open face of the labyrinth path 34.
• the labyrinth path inlet 32 extends to the upper edge 82 of the member
• the hollow conical member 36 Adjacent to inlet 32 is a short circuiting outlet, labyrinth aperture 58 used during priming. Intermediate outlets are seen at 48 and 56. When minimum flow rates are required, the full length of the labyrinth path is used and fluid exits the labyrinth path 34 through aperture 40.
• the hollow conical member 36 is suitably made of a soft plastic such as polypropylene or PVC.
• FIG. 5 there is depicted a further embodiment 84 of the flow regulator, which is similar to 10 except as will be described.
• the included angle of conical member outer face 86 is between 176 and
• the diaphragm 88 completely covers the upper edge 90 of the hollow conical member 92, without leaving any gap. However an aperture 94 in the diaphragm 88, and an aligned aperture 95 in the hollow conical member 92 allows fluid to flow from the first chamber 96 to the entrance 98 of the labyrinth path 34.
• FIG. 6 shows a flow regulator 100 similar to that shown in FIG. 1 , wherein the upper inlet 102 of first chamber 14 is connected to receive fluid from a syringe 104.
• a syringe 104 typically has a capacity of 50 - 60 ml.
• Advantageously syringe 104 is provided with means urging the syringe piston 106 towards first chamber upper inlet 102.
• Such means in this embodiment comprises a tensioned elastic element 108 disposed between an exposed extremity 110 of piston 106 and anchor elements 112 attached to the syringe body 114.
• fluid flow is adjustable between about 1 to about 10 ml per hour.
• the syringe 104 is shown as a separate but connected unit, this being advantageous in allowing the use of a standard low-cost syringe. Nevertheless it will be understood that the syringe body 114 and the regulator housing 12 can be manufactured if required as one integral unit.
• the regulator 100 is primed while short-circuiting the labyrinth path 34 as explained with reference to FIG. 1.
• the syringe 104 is then filled, connected to the regulator 100, and air is discharged from the regulator as the elastic element 108 applies pressure on the syringe piston 106 to initiate fluid flow.
• Flow rate is then adjusted to a desired flow rate as explained with reference to FIG. 1.

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• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Public Health (AREA)
• General Physics & Mathematics (AREA)
• Anesthesiology (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Hematology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Fluid Mechanics (AREA)
• Veterinary Medicine (AREA)
• Vascular Medicine (AREA)
• Automation & Control Theory (AREA)
• Infusion, Injection, And Reservoir Apparatuses (AREA)
• Fuel-Injection Apparatus (AREA)
• Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
• Safety Valves (AREA)
• Paper (AREA)
• Magnetically Actuated Valves (AREA)
• Vehicle Body Suspensions (AREA)
• Flow Control (AREA)

Applications Claiming Priority (3)

Publications (3)

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Family Applications (1)

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• 1998
  • 1998-12-06 IL IL12740698A patent/IL127406A/en not_active IP Right Cessation
• 1999
  • 1999-11-29 DE DE1999635528 patent/DE69935528T2/de not_active Expired - Lifetime
  • 1999-11-29 AU AU14069/00A patent/AU1406900A/en not_active Abandoned
  • 1999-11-29 WO PCT/IL1999/000643 patent/WO2000033896A2/en active IP Right Grant
  • 1999-11-29 AT AT99973262T patent/ATE356642T1/de not_active IP Right Cessation
  • 1999-11-29 US US09/857,484 patent/US6598618B1/en not_active Expired - Lifetime
  • 1999-11-29 EP EP99973262A patent/EP1135179B1/de not_active Expired - Lifetime

Non-Patent Citations (2)

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